1. Field of the Invention
The present invention relates to a system and method for effectively generating minus ions by utilizing negative ion exchange functionality included in material for walls, based on the discovery that wall surfaces made of natural volcanic ejecta (volcanic ash sediment) as a main component have high minus ion generation functionality.
2. Related Background Art
In recent years, study in the utilization of “shirasu”, a volcanic ejecta and found in abundant deposits, has been carried out in the field of construction. Shirasu is a generic name given to white lumps of volcanic ejecta and the secondary sedimentation originating therefrom, which are widely distributed about the Southern Kyushu area of Japan. Conventionally, almost all examples of using shirasu have been as building material that has undergone secondary processing; however, the inventor implements non-processed shirasu as a finishing coat material to be used in construction (U.S. Pat. No. 6,171,655 and Japanese Patent Application No. 2000-391856), and is experiencing commercial success.
Crystallization differentiation occurs due to the cooling of high-temperature magma, thereby clustering and crystallizing the main components of magma, for example, SiO2, Al2O3, Fe2O3, FeO, MgO, CaO, Na2O, K2O together into minerals. Soon thereafter these are violently ejected, forming this shirasu. Shirasu comprises approximately 30% crystallized minerals and approximately 70% non-crystalline volcanic glass.
Non-crystalline volcanic glass takes on a porous pumice-like constitution due to the vigorous emission of the volatile components of magma, and comprises 65 to 73% SiO2, 12 to 16% Al2O3, 2 to 4% CaO, 3 to 4% Na2O, 2 to 4% K2O, and 1 to 3% iron. The crystallized minerals comprise mostly plagioclase, but also include some hypersthene, quartz, augite, magnetite and the like.
Examples given for shirasu processing include the utilization of “shirasu balloons”, which are obtained through rapid heating. When shirasu is heated, softening of glass contained in the shirasu and evaporation of water contained in the shirasu occur at the same time to cause foaming, and forming the hollow spherical bodies of what is referred to as “shirasu balloons” (developed in 1970 by Kyushu Kogyo Gijutsu Shiken Kenkyusho). Shirasu balloons are naturally produced through high-temperature heating by magma, and are included within shirasu. The approximate size of shirasu balloons naturally included in shirasu range from 30 to 600 μm, and characteristics include being non flammable, a low bulk density, a high melting point, low thermal conductivity, low dielectric constant, non-toxic, and do not emit toxic gas. In recent years, shirasu balloons having sizes ranging from 600 to 3000 μm have been artificially produced. Light-weight industrial coatings capable of thick application have been produced by secondary processing of such shirasu balloons. In addition, usage in construction materials such as for ceiling materials that are light and do not require much strength has also come to enjoy full-scale use; moreover, progress in the development of polymer composite materials using pulverized shirasu is continuing.
In comparison with technology where shirasu undergoes secondary processing, direct commercialization of non-processed shirasu has not existed for very long. This is due to the fact that shirasu has extremely high flow properties in water. Evidence of the high flow properties in water can be seen in, for example, conditions where ground level shirasu is eaten away and countless eroded valleys have appeared.
If amalgamated substance of shirasu and water is applied as it is as material for a wall, cracks will appear in the surface when it dries. Furthermore, in addition to cracks in the surface due to drying, a water flow phenomenon also occurs, where water in the surface of the wall descends and flows down on the surface of the wall.
The inventors have overcome problems such as cracks and water flow by adding a predetermined percentage of a predetermined material that includes a clay component having high water-retentiveness and have achieved commercialization of a wall material that effectively uses the natural volcanic ash material shirasu, as disclosed in the above-mentioned U.S. patent. Not only is this wall material currently enjoying commercial success, but is also gaining favorable evaluation from, for example, the Kyushu Kogyo Gijutsu Shikenjo, the Kagoshima Prefectural Institute of Industrial Technology (in particular, the Materials Division), and the Miyazaki Prefecture Industrial Technology Center. The development and commercialization of shirasu wall materials has had an extremely high effect on market activity such that the price of shirasu volcanic ash, which used to be traded in the neighborhood of JPY3000 per 10 tons, has become approximately JPY10,000 per 10 kg.